称重传感器(中英)

称重传感器简介Introduction to Load Cells
什么是称重传感器？What is load cell
称重传感器是将力转换为可测量的电信号输出的传感器。

尽管称重传感器种类繁多，但基于应变计的称重传感器是最常用的类型。

A load cell is a transducer which converts force into a measurable electrical output. Although there are many varieties of load cells, strain gage based load cells are the most commonly used type.
称重传感器发展历史Load Cell History
在应变计称重传感器成为工业称重领域常用的称重方法之前，人们普遍使用机械杠杆秤。

机械秤可以称量从药丸到列车车厢的所有物品，只要适当校准和维护，即可保证足够的精度和可靠性。

其工作方式包括利用重量平衡机制或者检测由机械杠杆产生的力。

最早的预应变计测力传感器包括液压和气动两种设计。

1843 年，英国物理学家Charles Wheatstone 爵士发明了可测量电阻的电桥电路。

惠斯通电桥电路非常适用于测量应变计中的电阻变化。

尽管第一台粘贴式电阻丝应变计早在二十世纪四十年代就已开发出来，但直到现代电子技术蓬勃发展，这项技术才有了技术和经济可行性。

而从那时起，应变计就广泛地应用在机械秤和独立称重传感器中。

今天，除了某些实验室还在使用精密的机械天平外，应变计称重传感器已在称重行业占据了统治地位。

气动称重传感器有时应用在对本质安全性和安全卫生性要求较高的领域；液压称重传感器不需要电源，因此适用于远程应用。

应变计称重传感器可提供0.03% 到0.25% 的满量程精度，适用于几乎所有工业应用。

Before strain gage-based load cells became the method of choice for industrial weighing applications, mechanical lever scales were widely used. Mechanical scales can weigh everything from pills to railroad cars and can do so accurately and reliably if they are properly calibrated and maintained. The method of operation can involve either the use of a weight balancing mechanism or the detection of the force developed by mechanical levers. The earliest, pre-strain gage force sensors included hydraulic and pneumatic designs. In 1843, English physicist Sir Charles Wheatstone devised a bridge circuit that could measure electrical resistances. The Wheatstone bridge circuit is ideal for measuring the resistance changes that occur in strain gages. Although the first bonded resistance wire strain gage was developed in the 1940s, it was not until modern electronics caught up that the new technology became technically and economically feasible. Since that time, however, strain gages have proliferated both as mechanical scale components and in stand-alone load cells. Today, except for certain laboratories where precision mechanical balances are still used, strain gage load cells dominate the weighing industry. Pneumatic load cells are sometimes used where intrinsic safety and hygiene are desired, and hydraulic load cells are considered in remote locations, as they do not require a power supply. Strain gage load cells offer accuracies from within 0.03%
to 0.25% full scale and are suitable for almost all industrial applications.
称重传感器工作原理：Load Cell Operating Principles:
称重传感器的设计可按生成的输出信号类型（气动、液压、电气）或重量检测方式（弯梁、剪切梁、压力、张力等）区分。

Load cell designs can be distinguished according to the type of output signal generated (pneumatic, hydraulic, electric) or according to the way they detect weight (bending, shear, compression, tension, etc.)
液压称重传感器是一种力平衡设备，通过内部填充液体的压力变化测量重量。

在滚动隔膜式液压称重传感器中，作用在集料器上的负载或力将传递到活塞，进而压挤封闭在弹性隔膜腔中的填充液体。

力越大，液压液体的压力就越大。

此压力值可在本地指示，也可发送到其它位置，以实现远程指示或控制。

输出具有线性特性，相对来说不易受填充液体的容量和温度的影响。

如果称重传感器经过适当的安装和校准，则精度可达到满量程0.25% 以内，适用于大多数的过程称重应用。

由于这种传感器不使用电气元件，因此非常适用于危险区域。

典型的液压称重传感器应用包括罐体、箱体和漏斗称重。

为了达到最高的精度，应在罐体的每个支撑点放置一个称重传感器，通过将这些传感器的输出求和，得出罐体的总重量。

Hydraulic load cells are force -balance devices, measuring weight as a change in pressure of the internal filling fluid. In a rolling diaphragm type hydraulic load cell, a load or force acting on a loading head is transferred to a piston that in turn compresses a filling fluid confined within an elastomeric diaphragm chamber. As force increases, the pressure of the hydraulic fluid rises. This pressure can be locally indicated or transmitted for remote indication or control. Output is linear and relatively unaffected by the amount of the filling fluid or by its temperature. If the load cells have been properly installed and calibrated, accuracy can be within 0.25% full scale or better, acceptable for most process weighing applications. Because this sensor has no electric components, it is ideal for use in hazardous areas. Typical hydraulic load cell
applications include tank, bin, and hopper weighing. For maximum accuracy, the weight of the tank should be obtained by locating one load cell at each point of support and summing their outputs.
气动称重传感器也利用力平衡原理。

这些设备采用多个阻尼腔，可实现比液压设备更高的精度。

在一些设计中，第一个阻尼腔用作皮重腔。

气动称重传感器经常用于对清洁程度和安全性要求较高的行业，可测量相对较小的重量。

对温度变化不敏感以及固有的防爆能力是这种称重传感器的两大优点。

此外，即使隔膜破裂，其中的液体也不会造成污染。

其缺点是，响应速度相对较慢，并且需要清洁干燥的调节空气或氮气。

Pneumatic load cells also operate on the force-balance principle. These devices use multiple dampener chambers to provide higher accuracy than can a hydraulic device. In some designs, the first dampener chamber is used as a tare weight chamber. Pneumatic load cells are often used to measure relatively small weights in industries where cleanliness and safety are of prime concern. The advantages of this type of load cell include their being inherently explosion proof and insensitive to temperature variations. Additionally, they contain no fluids that might contaminate the process if the diaphragm ruptures. Disadvantages include relatively slow speed of response and the need for clean, dry, regulated air or nitrogen.
应变计称重传感器可将作用在其上的负载转换为电信号。

应变计粘合在梁或结构构件上，这些部件在承重时会发生变形。

大多数情况下，使用四个应变计可获得最高的敏感度和温度补偿。

通常两个应变计用于测量张力，另外两个用于测量压力，这些应变计相互连接以实现补偿调整（如图7-2 所示）。

承重时，应力引发的应变计电阻变化与负载成正比。

随着应变计称重传感器的精度持续提高、单位成本持续下降，其它称重传感器正逐步退出历史舞台。

Strain-gage load cells convert the load acting on them into electrical signals. The gauges themselves are bonded onto a beam or structural member that deforms when weight is applied. In most cases, four strain gages are used to obtain maximum sensitivity and temperature compensation. Two of the gauges are usually in tension, and two in compression, and are wired with compensation adjustments as shown in Figure 7-2. When weight is applied, the strain changes the electrical resistance of the gauges in proportion to the load. Other load cells are fading into obscurity, as strain gage load cells continue to increase their accuracy and lower their unit costs.
称重传感器类型Types of Load Cells
压力称重传感器
压力称重传感器通常采用整体按钮式设计。

这种传感器适合安装在空间有限的区域， 具有极佳的长期稳定性。

Compression Load Cells
Compression load cells often have an integral button design. They are ideal for mounting where
space is restricted. They offer excellent long term stability.
压力/张力称重传感器
压力/张力称重传感器可用于负载在压力和张力之间来回转换的应用。

这种传感器适用于空间有限的环境， 其带螺纹的端头可方便安装。

Compression/Tension Load Cells Compression/tension load cells can be used for applications where the load may
go from tension to compression and vice versa. They are ideal for space restricted environments. Threaded ends facilitate easy installation.
S 梁称重传感器
S 梁称重传感器因其 S 状的外形而得名。

S 梁称重传感器可在受到张力或压力时提供相应的输出， 适用于罐内液位、漏斗和地秤等应用。

它具有极佳的抗侧能力。

S-Beam Load Cells
S-Beam load cells get their name from their S shape. S-Beam load cells can provide an output if
under tension or compression. Applications include tank level, hoppers and truck scales. They provide superior side load rejection.
弯梁式称重传感器
适用于需要多个称重传感器的应用，例如罐体称重和工业过程控制。

它采用低外形结构，适用于空间有限的区域。

Bending Beam Load Cells
Used in multiple load cell applications, tank
weighing and industrial process control. They feature low profile construction for integration into restricted areas.
平台单点式称重传感器
平台单点式称重传感器用于商业和工业称重系统。

无论负载处于平台的哪个位置，均可提供精确的读数。

Platform and Single Point Load Cells
Platform and single point load cells are used to commercial and industrial weighing systems. They
provide accurate readings regardless of the position of the load on the platform.
筒式称重传感器
筒式称重传感器适用于单称重和多称重应用。

许多此类传感器均采用全不锈钢设计，提供全方位的密封保护，适用于冲洗和潮湿区域。

Canister Load Cells
Canister load cells are used for single and multi-weighing applications. Many feature
an all stainless steel design and are hermetically sealed for washdown and wet areas.
低外形称重传感器
包括压力和张力/压力称重传感器。

它采用方便安装的安装孔和内螺纹。

经常用于称重研究和流向力监视。

Low Profile Load Cells
Compression and tension/compression load cells.
Mounting holes and female threads provide easy installation. Used frequently in weighing research
and in-line force monitoring.。